RESUMO
Coccidiosis remains a significant threat to the welfare of game farm-reared pheasants in the United States. Although lasalocid has been demonstrated to be effective against pheasant specific coccidia, information regarding its safety in this species is lacking. The purpose of this study was to gather data on the safety of lasalocid when fed to Chinese ring-necked pheasants at one, two, and three times the recommended high dose of lasalocid used for prevention of coccidiosis in other poultry at three times the normal treatment period. Pheasant chicks (approximately 1 day-old; n = 160) were randomly blocked by sex into four treatment groups and given their respective diets continuously for 6 wk. No significant differences were observed in overall feed consumption, weight gain, feed conversion rates, clinical pathology measurements, or tissue gross and histopathologic evaluations between controls and treatment groups associated with lasalocid administration. Based on the results of this study it appears that lasalocid fed at the recommended rate of 125 ppm is safe in Chinese ring-necked pheasants.
Assuntos
Coccidiose/veterinária , Coccidiostáticos/efeitos adversos , Galliformes , Lasalocida/efeitos adversos , Doenças das Aves Domésticas/tratamento farmacológico , Fenômenos Fisiológicos da Nutrição Animal/efeitos dos fármacos , Animais , Coccidiose/tratamento farmacológico , Coccidiostáticos/uso terapêutico , Relação Dose-Resposta a Droga , Comportamento Alimentar/efeitos dos fármacos , Feminino , Lasalocida/uso terapêutico , Masculino , Aumento de Peso/efeitos dos fármacosRESUMO
BACKGROUND: Mastitis is a major disease of dairy cattle. Given the recent emergence of methicillin-resistant Staphylococcus aureus as a cause of bovine mastitis, new intramammary (IMA) treatments are urgently required. Lasalocid, a member of the polyether ionophore class of antimicrobial agents, has not been previously administered to cows by the IMA route and has favorable characteristics for development as a mastitis treatment. This study aimed to develop an IMA drug delivery system (IMDS) of lasalocid for the treatment of bovine mastitis. METHODS: Minimum inhibitory concentrations (MICs) were determined applying the procedures recommended by the Clinical and Laboratory Standards Institute. Solid dispersions (SDs) of lasalocid were prepared and characterized using differential scanning calorimetry and Fourier transform infrared spectroscopy. IMDSs containing lasalocid of micronized, nano-sized, or as SD form were tested for their IMA safety in cows. Therapeutic efficacy of lasalocid IMDSs was tested in a bovine model involving experimental IMA challenge with the mastitis pathogen Streptococcus uberis. RESULTS: Lasalocid demonstrated antimicrobial activity against the major Gram-positive mastitis pathogens including S. aureus (MIC range 0.5-8 µg/mL). The solubility test confirmed limited, ion-strength-dependent water solubility of lasalocid. A kinetic solubility study showed that SDs effectively enhanced water solubility of lasalocid (21-35-fold). Polyvinylpyrrolidone (PVP)-lasalocid SD caused minimum mammary irritation in treated cows and exhibited faster distribution in milk than either nano or microsized lasalocid. IMDSs with PVP-lasalocid SD provided effective treatment with a higher mastitis clinical and microbiological cure rate (66.7%) compared to cloxacillin (62.5%). CONCLUSION: Lasalocid SD IMDS provided high cure rates and effectiveness in treating bovine mastitis with acceptable safety in treated cows.
Assuntos
Antibacterianos/administração & dosagem , Indústria de Laticínios , Lasalocida/administração & dosagem , Glândulas Mamárias Animais/efeitos dos fármacos , Mastite Bovina/tratamento farmacológico , Infecções Estreptocócicas/tratamento farmacológico , Animais , Antibacterianos/efeitos adversos , Antibacterianos/química , Antibacterianos/metabolismo , Varredura Diferencial de Calorimetria , Bovinos , Química Farmacêutica , Vias de Administração de Medicamentos , Feminino , Cinética , Lasalocida/efeitos adversos , Lasalocida/química , Lasalocida/metabolismo , Glândulas Mamárias Animais/microbiologia , Glândulas Mamárias Animais/fisiopatologia , Mastite Bovina/diagnóstico , Mastite Bovina/microbiologia , Mastite Bovina/fisiopatologia , Testes de Sensibilidade Microbiana , Leite/metabolismo , Nanopartículas , Povidona/química , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Infecções Estreptocócicas/diagnóstico , Infecções Estreptocócicas/microbiologia , Infecções Estreptocócicas/fisiopatologiaRESUMO
This paper characterizes the light microscopic and ultrastructural lesions in peripheral nerves caused by feeding lasalocid and roxarsone to broiler chickens. The birds were given three different doses of each compound: the standard industrial dose, 150% of the standard dose, and 200% of the standard dose. It was necessary to deprive the birds of water for 4 hours daily and heat-stress them in order to reproduce the lesion. Each compound caused mild microscopic lesions of swollen axons, digestion chambers, shrunken axons, or vacuoles where axons were missing. Ultrastructural changes included formation of myelin ellipsoids, vacuoles within or beneath the myelin sheath, and unraveling of myelin. These lesions were most frequently found in the birds receiving lasalocid.
Assuntos
Galinhas , Lasalocida/efeitos adversos , Doenças do Sistema Nervoso Periférico/veterinária , Roxarsona/efeitos adversos , Ração Animal , Animais , Relação Dose-Resposta a Droga , Masculino , Microscopia Eletrônica/veterinária , Nervos Periféricos/ultraestrutura , Doenças do Sistema Nervoso Periférico/induzido quimicamente , Doenças do Sistema Nervoso Periférico/patologiaRESUMO
An investigation involving 640 turkeys demonstrated that the inclusion of lasalocid continuously from day-old to 16 weeks of age, at levels up to 375 ppm in the feed, produced no adverse effects; furthermore, the inclusion of 125 ppm lasalocid in the feed was compatible with the administration of 250 ppm tiamulin in the drinking water continuously for five days to turkeys over the same age range.
Assuntos
Antibacterianos/efeitos adversos , Lasalocida/efeitos adversos , Perus/fisiologia , Ração Animal , Animais , Peso Corporal , Coccidiose/prevenção & controle , Coccidiose/veterinária , Diterpenos/efeitos adversos , Ingestão de Líquidos , Ingestão de Alimentos , Feminino , Lasalocida/administração & dosagem , Masculino , Tamanho do Órgão , Doenças das Aves Domésticas/prevenção & controle , Perus/sangue , Perus/crescimento & desenvolvimentoRESUMO
Two growth experiments were conducted to evaluate in broiler chicks the compatibility between lasalocid medication in the feed (at 90 or 125 ppm) and a long-term administration of chloramphenicol either via the feed (500 ppm) or via the drinking water (500 mg/liter). The simultaneous administration of lasalocid and chloramphenicol generally caused severe growth depression, decreased feed intake and impaired feed conversion. Several chicks showed evident symptoms of intoxication, such as ataxia, leg weakness and paralysis. The development and frequency of these symptoms were dependent on the dosage of lasalocid and on the duration of the simultaneous administration. Biochemical examinations (Experiment 2) revealed in the affected chicks significant changes in several parameters, in particular a markedly increased activity of creatine kinase and GOT in the plasma. It confirmed that the observed leg weakness and paralysis were caused by myodegeneration.
Assuntos
Galinhas/fisiologia , Cloranfenicol/efeitos adversos , Lasalocida/efeitos adversos , Ração Animal , Animais , Aspartato Aminotransferases/sangue , Ataxia/induzido quimicamente , Ataxia/veterinária , Peso Corporal/efeitos dos fármacos , Galinhas/crescimento & desenvolvimento , Creatina Quinase/sangue , Incompatibilidade de Medicamentos , Quimioterapia Combinada , Ingestão de Alimentos/efeitos dos fármacos , Feminino , Masculino , Paralisia/induzido quimicamente , Paralisia/veterinária , Doenças das Aves Domésticas/induzido quimicamenteRESUMO
Utilization of amino acids, sulfur-containing amino acid (SAA) in particular, is little affected by antibiotic and anticoccidial compounds. Coccidiosis (i.e., Eimeria acervulina infection) likewise seems to have little effect on SAA utilization. Copper sulfate, a commonly used antibacterial-antifungal compound (used at levels of 100-250 mg/kg diet), interacts with SAA. Hence, at upper levels of copper ingestion (i.e., 250 mg/kg and higher), copper binds SH compounds such as cysteine and reduced glutathione. Dietary SAA requirements are increased in both chicks and rats by dietary copper levels of 250 or 500 mg/kg. Hepatic copper deposition is enhanced by copper feeding and also by E. acervulina infection. These two effects, moreover, appear to be additive. The organic arsenic compound, roxarsone, interacts with SAA also, but in a different way. Thus, whereas added dietary cysteine partially ameliorates copper toxicity due to the binding of copper by cysteine-SH with subsequent excretion, roxarsone toxicity (i.e., 500 mg/kg diet) is exacerbated by supplemental cysteine.
Assuntos
Aminoácidos/metabolismo , Galinhas/fisiologia , Coccidiostáticos/farmacologia , Doenças das Aves Domésticas/fisiopatologia , Aminoácidos Sulfúricos/metabolismo , Animais , Antibacterianos/efeitos adversos , Arsenicais/efeitos adversos , Coccidiose/fisiopatologia , Cobre/efeitos adversos , Lasalocida/efeitos adversos , Monensin/efeitos adversosRESUMO
The ionophores A23187 and X537A, which increase the permeability of cell membranes to calcium and other divalent cations, produced significant elevation of intraocular pressure in rabbits. Topical instillation of these ionophores in concentrations of 1.0 and 0.1 per cent were effective. Aqueous humor protein and facility of outflow were similar in ionophore-treated and control eyes. Pretreatment with indomethacin did not block the intraocular pressure rise induced by A23187. Alterations of intracellular calcium might control cellular processes within the eye as in many other biological systems.